1. Field of the Invention
The present invention relates to a washer (washing machine) having a partial washing apparatus that removes dirt from a partially soiled article to be washed by means of a washing liquid agitated by supersonic vibration, and thus the present invention relates generally to a washing apparatus.
2. Description of the Prior Art
Shirts soiled with obstinate dirt at their collars and cuffs, or socks so soiled, need to be subjected to preparatory washing before being washed in a washing machine. Such preparatory washing, however, is achieved by rubbing an article to be washed by hand, or washing it by hand with a brush, and thus not only takes time and labor but also damages the fiber of which the article is made.
To overcome this problem, Japanese Laid-Open Patent Application H4-2247093 proposes a partial washing apparatus that removes dirt from a partially soiled article to be washed by means of a washing liquid agitated by supersonic vibration. FIG. 29 is a perspective view of a washing machine provided with this partial washing apparatus. The partial washing apparatus 204 is composed essentially of a jet nozzle 201 that is fixed to a washing machine proper 202 so as to be placed above a washing sink 203, a washing liquid feeder 205 for feeding a washing liquid to the jet nozzle 201, and a supersonic vibration generator 206 for generating supersonic vibration inside the jet nozzle 201.
When the washing liquid feeder 205 and the supersonic vibration generator 206 are activated, a jet of the washing liquid agitated by the supersonic vibration applied thereto from the jet nozzle 201 is emitted into the washing sink 203. By exposing a soiled portion of an article to be washed to this jet of the washing liquid, it is possible to separate and remove the soil as a result of the synergistic effect of the vibration acceleration and the jet pressure of the washing liquid.
However, in this washing machine, the jet nozzle 201, which is fixed so as to be placed above the washing sink 203, protrudes toward the center of an opening 207 to the washing sink 203. Thus, the jet nozzle 201 becomes an obstacle when articles to be washed are put into the washing sink 203 or when washed articles are taken out of it. In particular when washed articles are taken out of the washing sink 203, they may be caught on the jet nozzle 201 in such a way as to damage it.
The jet nozzle 201 is designed to retract inside the washing machine proper 202 when a lid 208 is closed. Accordingly, the jet nozzle 201 is fixed at about the same level as the opening 207 that is located at a height of about 750 to 800 mm above the floor. Thus, the jet nozzle 201 is fixed at a level somewhat lower than the hands of an average user. This requires the user to keep his or her body bent forward while performing partial washing. In the first place, users of different stature have their hands at different levels when doing such washing. Therefore, placing the jet nozzle 201 at a fixed height as in this washing machine forces users to do washing in uncomfortable positions, and thus increases their fatigue unnecessarily.
Moreover, this type of partial washing apparatus uses supersonic vibration in a comparatively high frequency range of about 500 kilohertz to several megahertz. In addition, in the partial washing apparatus described above, the supersonic vibration is squeezed by the jet nozzle 201 to obtain a higher energy density. As a result, the washing liquid emitted from the jet nozzle 201 has a flow rate of about several meters per second, and thus, on hitting an article to be washed, it often splashes around, making the surroundings of the washing machine wet.
Moreover, the supersonic vibration of the washing liquid emitted from the jet nozzle 201 has the maximum intensity at the tip of the jet nozzle 201, and its intensity abruptly decays at distances of several tens of millimeters or longer from the tip of the jet nozzle 201, though how it decays depends somewhat on the frequency of the supersonic vibration. Accordingly, a satisfactory washing effect can be achieved only when an article to be washed is held within a limited range of distances from the jet nozzle 201.
For example, if the supersonic vibration has a frequency of 1 MHz, an article to be washed needs to be washed at a distance of about 20 mm from the tip of the jet nozzle 201. However, in the washing machine described above, it is difficult to hold an article to be washed at a fixed distance from the jet nozzle 201, and therefore, depending on how the article is actually washed, a quite unsatisfactory washing effect may result.
Moreover, supersonic vibration in a high frequency range reaches so deep into the human body that the portion of the body affected by it feels sore, and also is believed to have adverse effects on cartilage. In view of this, with the partial washing apparatus 204 described above, which have no protective means for preventing the user's hands and fingers from touching the washing liquid agitated by supersonic vibration in a relatively high frequency range, the user may be exposed to the risk of suffering injuries to his or her hands.
Moreover, in cases where tap water is used as the washing liquid for partial washing, the detergent applied beforehand to an article to be washed does not dissolve into it well. Thus, to obtain a satisfactory washing effect, more detergent needs to be used, which adds to the pollution of the environment through sewage.
In the first place, it is troublesome to apply detergent for partial washing beforehand to every soiled portion of articles to be washed. Then, a jet of the washing liquid is emitted to each soiled portion to which the detergent has thus been applied beforehand. At this time, the washing liquid is emitted at a flow rate as high as several liters per minute, and thus washes the detergent away, leading to an unsatisfactory washing effect. Moreover, obstinate dirt may require repeated application of the detergent, which adds to the trouble of such partial washing.
Moreover, not only to conform to the recent trend toward larger washing capacities, but also to offer more sophisticated functions, modern washing machines have come to have more and more complicated constructions. This makes it difficult to house inside the washing machine proper 202 a washing liquid feeder 205 for feeding the washing liquid into the washing sink 203. The washing liquid feeder 205 may be arranged so as to protrude outside the washing machine proper, but this makes the washing machine difficult to install and handle, because nowadays less and less space tends to be left for a washing machine as a clothes dryer and other appliances become more and more popular.
On the other hand, in recent years, various types of detergent have been developed and are commercially available for different degrees of soil, different kinds of fiber, and different conditions of other factors. For example, there are available detergent for oil stains, detergent for light dirt, detergent for clothes labeled as fit for dry cleaning only, and detergent for clothes labeled as requiring no ironing. By applying appropriate types of detergent to articles to be washed before subjecting them to partial washing, it is possible to obtain a satisfactory washing effect with various types of articles. This applies not only to partial washing, but also to ordinary washing, where using different types of detergent for different conditions also makes it possible to do washing in manners most suitable for given types of articles.
Japanese Laid-Open Utility Model Application No. H3-24081 discloses a washing machine that can feed different types of washing liquid automatically. As shown in FIG. 30, this washing machine is provided with a plurality of liquid-feed tanks 103 each having a check valve 101 and a solenoid valve 102. A controller 104 opens the solenoid valves 102 to appropriate degrees, and drives a compressed air feeder 105 to feed compressed air to air inlets 107 and 108 of a cylinder pump 106 so as to move a piston 109 up and down. This permits the washing liquids stored in the individual liquid-feed tanks 103 to be sucked up sequentially and fed to the articles to be washed put in the washing sink 110.
However, this washing machine, though provided with a plurality of liquid-feed tanks 103, simply drives the cylinder pump 106 in accordance with a program stored beforehand so that the detergents stored in the individual liquid-feed tanks 103 are sucked up sequentially and fed to the washing sink 110. That is, this washing machine does not permit the user to select detergents most appropriate for given types of articles to be washed.
Moreover, this washing machine requires that its liquid-feed tanks 103 be each provided with a check valve 101 and a solenoid valve 102, and in addition requires the provision of a compressed air feeder 105 and a cylinder pump 106. Thus, this washing machine has too complicated a construction to be practical.